[TallblokeUK]

On PHP 8.1 and later, opening an existing snippet in the editor logs Deprecated: strip_tags(): Passing null to parameter #1 ($string) of type string is deprecated in wp-admin/admin-header.php on line 41. The browser tab also has no page title on that screen.

Reported at https://wordpress.org/support/topic/update-to-4-0-0-deprecated-strip_tags-passing-null-to-parameter-1/

Cause

WordPress looks up a screen's title in the admin menu. Since 4.0.0 the Edit Snippet page is registered outside the menu, so no title is found, and the admin header passes null to strip_tags().

Changes

• The edit screen sets its title when it loads. The Add New and other Snippets screens are unaffected.

Verification

• Reproduced on 4.0.0 (PHP 8.1): one notice when editing an existing snippet and none on the other Snippets screens. With the change there is no notice, and the tab reads "Edit Snippet".
• A new test in Edit_Menu_Test checks the title WordPress resolves for the edit screen. It fails without the change.
• The full PHPUnit suite passes and lint:php is clean.